1. Technical Field
This invention relates to the creation of vacuum for one or more pick and place mechanisms mounted in a pick and place machine.
2. Related Art
For the generation of vacuum, it is standard to use compressed air and a venturi. The compressed air blown into the venturi with high speed generates vacuum that can then be connected to the pick and place mechanisms, such as nozzles or vacuum activated grippers, via a manifold, hoses, couplings, and often a valve to connect/disconnect the vacuum from each pick and place mechanism. This way multiple pick and place mechanisms can be connected to single vacuum generator.
One disadvantage of the existing design is that any foreign matter such dirt, dust and other pollution, that is drawn into the pick and place mechanism by the vacuum will pass through the valves, through the hoses and through the couplings and the manifold, before it can be blown out of the system at the venturi. This leads to sticky valves and polluted hoses and manifold. A second disadvantage for the existing design is that because the valves are operating under vacuum conditions, lubricants tend to evaporate more quickly, which leads to failure of the valve(s). Another disadvantage of the current design is that often the vacuum generator is on a stationary part of the machine while the pick and place mechanism itself has to be able to rotate, sometimes over multiple axes. This is achieved using couplings with seals. However any leak of these seals will both diminish the ultimate vacuum force applied to the component part at the pick and place mechanism and also will allow more foreign matter to be drawn into the mechanism at any failed seal location. Still another disadvantage of the current design is that the air rushes through the venturi continuously, whether the mechanism is operating to pick a component or not. With machines often waiting for boards or parts to be replenished, this is wasteful and often noisy.
A need exists for a vacuum generation system that overcomes at least one of the aforementioned, and other, deficiencies in the art.